Dihydropyrimidines

ABSTRACT

The invention relates to compounds of the formulae

The present invention relates to novel dihydropyrimidine compounds, toprocesses for their preparation and to their use as medicaments, inparticular for the treatment and prophylaxis of hepatitis B.

Dihydropyrimidines having cardiovascular action are already known fromthe publication EP 103 796 A2.

The present invention now provides novel dihydropyrimidine compounds ofthe general formula (I)

or their isomeric form (Ia)

in which

-   R¹ represents phenyl, furyl, thienyl, triazolyl, pyridyl, cycloalkyl    having 3 to 6 carbon atoms or represents radicals of the formulae-    where the abovementioned ring systems are optionally mono- or    polysubstituted by identical or different substituents selected from    the group consisting of halogen, trifluoromethyl, nitro, cyano,    trifluoromethoxy, carboxyl, hydroxyl, (C₁-C₆)-alkoxy,    (C₁-C₆)-alkoxycarbonyl and (C₁-C₆)-alkyl, which for its part may be    substituted by aryl having 6 to 10 carbon atoms or halogen, and/or    the ring systems mentioned are optionally substituted by groups of    the formulae —S—R⁶, NR⁷R⁸, CO—NR⁹R¹⁰, SO₂—CF₃, and -A-CH₂—R¹¹,-    in which    -   R⁶ represents phenyl which is optionally substituted by halogen,    -   R⁷, R⁸, R⁹ and R¹⁰ are identical or different, and each        represents hydrogen, phenyl, hydroxyl-substituted phenyl,        hydroxyl, (C₁-C₆)-acyl or (C₁-C₆)-alkyl, which for its part may        be substituted by hydroxyl, (C₁-C₆)-alkoxycarbonyl, phenyl or        hydroxyl-substituted phenyl,    -   A represents a radical O, S, SO or SO₂,    -   R¹¹ represents phenyl which is optionally mono- to        polysubstituted by identical or different substituents selected        from the group consisting of halogen, nitro, trifluoromethyl,        (C₁-C₆)-alkyl and (C₁-C₆)-alkoxy,-   R² represents a radical of the formula —XR¹² or —NR¹³R¹⁴,    -   in which    -   X represents a bond or oxygen,    -   R¹² represents hydrogen, straight-chain or branched        (C₁-C₆)-alkoxycarbonyl or a straight-chain, branched or cyclic        saturated or unsaturated (C₁-C₈)-hydrocarbon radical which        optionally contains one or two identical or different hetero        chain members from the group consisting of O, CO, NH,        —NH—(C₁-C₄)-alkyl, —N—((C₁-C₄)-alkyl)₂, S and SO₂ and which is        optionally substituted by halogen, nitro, cyano, hydroxyl, aryl        having 6 to 10 carbon atoms or aralkyl having 6 to 10 carbon        atoms, heteroaryl or a group of the formula —NR¹⁵R¹⁶,        -   in which        -   R¹⁵ and R¹⁶ are identical or different, and each represents            hydrogen, benzyl or (C₁-C₆)-alkyl,    -   R¹³ and R¹⁴ are identical or different, and each represents        hydrogen, (C₁-C₆)-alkyl or cycloalkyl having 3 to 6 carbon        atoms,-   R³ represents hydrogen, amino or-    represents a radical of the formula-    represents formyl, cyano, trifluoromethyl or pyridyl, or-    represents a straight-chain, branched or cyclic saturated or    unsaturated hydrocarbon radical having up to 8 carbon atoms which is    optionally mono- or polysubstituted by identical or different    substituents from the group consisting of aryloxy having 6 to 10    carbon atoms, azido, cyano, hydroxyl, darboxyl,    (C₁-C₆)-alkoxycarbonyl, a 5- to 7-membered heterocyclic ring,    (C₁-C₆)-alkylthio and (C₁-C₆)-alkoxy, which for its part may be    substituted by azido or amino,-    and/or is substituted by triazolyl, which for its part may be    substituted up to 3 times by (C₁-C₆)-alkoxycarbonyl,-    and/or may be substituted by groups of the formulae —OSO₂—CH₃ or    (CO)_(a)—NR¹⁷R¹⁸,    -   in which    -   a represents a number 0 or 1,    -   R¹⁷ and R¹⁸ are identical or different, and each represents        hydrogen or aryl, aralkyl having 6 to 10 carbon atoms,    -    or represents (C₁-C₆)-alkyl which is optionally substituted by        (C₁-C₆)-alkoxycarbonyl, hydroxyl, phenyl or benzyl, where phenyl        or benzyl are optionally mono- or polysubstituted by identical        or different substituents from the group consisting of hydroxyl,        carboxyl, (C₁-C₆)-alkyl and (C₁-C₆)-alkoxy,    -    or (C₁-C₆)-alkyl is optionally substituted by groups of the        formulae NH—CO—CH₃ or NH—CO—CF₃,    -   or    -   R¹⁷ and R¹⁸ together with the nitrogen atom form a morpholine,        piperidinyl or pyrrolidinyl ring,-   or-   R³ represents phenyl which is optionally substituted by methoxy,-   or-   R² and R³ together form a radical of the formula-   R⁴ represents hydrogen, (C₁-C₄)-alkyl, (C₂-C₄)-alkenyl, benzoyl or    represents acyl having 2 to 6 carbon atoms,-   R⁵ represents pyridyl which is substituted up to 3 times by    identical or different substituents from the group consisting of    halogen, hydroxyl, cyano, trifluoromethyl, (C₁-C₆)-alkoxy,    (C₁-C₆)-alkyl, (C₁-C₆)-alkylthio, carbalkoxy, (C₁-C₆)-acyloxy,    amino, nitro, mono- and (C₁-C₆)-dialkylamino,    and salts thereof.

In the context of the invention, cycloalkyl having 3 to 6 carbon atomsor (C₃-C₆)-cycloalkyl represents cyclopropyl, cyclopentyl, cyclobutyl orcyclohexyl. Preference is given to cyclopentyl or cyclohexyl.

Aryl generally represents an aromatic radical having 6 to 10 carbonatoms. Preferred aryl radicals are phenyl and naphthyl.

In the context of the invention, (C₁-C₆)-acyl represents astraight-chain or branched acyl radical having 1 to 6 carbon atoms.Preference is given to a straight-chain or branched acyl radical having1 to 4 carbon atoms. Particularly preferred acyl radicals are acetyl andpropionyl.

In the context of the invention, (C₁-C₆)-alkyl represents astraight-chain or branched alkyl radical having 1 to 6 carbon atoms.Examples which may be mentioned are: methyl, ethyl, propyl, isopropyl,tert-butyl, n-pentyl and n-hexyl.

Preference is given to a straight-chain or branched alkyl radical having1 to 4 carbon atoms.

In the context of the invention, (C₂-C₆)-alkenyl represents astraight-chain or branched alkenyl radical having 2 to 5 carbon atoms.Preference is given to a straight-chain or branched alkenyl radicalhaving 3 to 5 carbon atoms. Examples which may be mentioned are:ethenyl, propenyl, alkyl, n-pentenyl and n-hexenyl.

In the context of the invention, (C₁-C₆)-alkoxy represents astraight-chain or branched alkoxy radical having 1 to 6 carbon atoms.Preference is given to a straight-chain or branched alkoxy radicalhaving 1 to 4 carbon atoms. Examples which may be mentioned are:methoxy, ethoxy and propoxy.

In the context of the invention, (C₁-C₆)-alkylthio represents astraight-chain or branched alkylthio radical having 1 to 6 carbon atoms.Preference is given to a straight-chain or branched alkylthio radicalhaving 1 to 4 carbon atoms. Examples which may be mentioned are:methylthio, ethylthio and propylthio.

In the context of the invention, (C₁-C₆)-alkoxycarbonyl represents astraight-chain or branched alkoxycarbonyl radical having 1 to 6 carbonatoms. Preference is given to a straight-chain or branchedalkoxycarbonyl radical having 1 to 4 carbon atoms. Examples which may bementioned are: methoxycarbonyl, ethoxycarbonyl and propoxycarbonyl.

A straight-chain, branched or cyclic, saturated or unsaturated(C₁-C₈)-hydrocarbon radical includes, for example, the above-described(C₁-C₆)-alkyl, (C₂-C₆)-alkenyl or (C₃-C₆)-cycloalkyl, preferably(C₁-C₆)-alkyl.

The compounds according to the invention may exist in stereoisomericforms which are related either as image and mirror image (enantiomers),or which are not related as image and mirror image (diastereomers). Theinvention relates both to the enantiomers or diastereomers and to theirrespective mixtures. The racemic forms can, just like the diastereomers,be separated in a known manner into the stereoisomerically pureconstituents.

The compounds of the present invention include the isomers of thegeneral formulae (I) and (Ia) and mixtures thereof. If R⁴ is hydrogen,the isomers (I) and (Ia) exist in a tautomeric equilibrium:

The substances according to the invention may also be present as salts.In the context of the invention, preference is given to physiologicallyacceptable salts.

Physiologically acceptable salts can be salts of the compounds accordingto the invention with inorganic or organic acids. Preference is given tosalts with inorganic acids, such as, for example, hydrochloric acid,hydrobromic acid, phosphoric acid or sulphuric acid, or to salts withorganic carboxylic or sulphonic acids, such as, for example, aceticacid, maleic acid, fumaric acid, malic acid, citric acid, tartaric acid,lactic acid, benzoic acid, or methanesulphonic acid, ethanesulphonicacid, phenylsulphonic acid, toluenesulphonic acid ornaphthalenedisulphonic acid.

Physiologically acceptable salts can also be metal or ammonium salts ofthe compounds according to the invention. Particular preference is givento, for example, sodium, potassium, magnesium or calcium salts, and alsoto ammonium salts which are derived from ammonia, or organic amines,such as, for example, ethylamine, di- or triethylamine, di- ortriethanolamine, dicyclohexylamine, dimethylaminoethanol, arginine,lysine, ethylenediamine or 2-phenylethylamine.

Preference is given to compounds of the general formulae (I) and (Ia)according to the invention

-   in which-   R¹ represents phenyl, furyl, thienyl, pyridyl, cyclopentyl or    cyclohexyl or represents radicals of the formulae-    where the abovementioned ring systems are optionally mono- or    disubstituted by identical or different substituents selected from    the group consisting of halogen, trifluoromethyl, nitro, SO₂—CF₃,    methyl, cyano, trifluoromethoxy, amino, hydroxyl, carboxyl,    methoxycarbonyl and radicals of the formulae —CO—NH—CH₂—C(CH₃)₃,    —CO—NH(CH₂)₂OH, —CO—NH—CH₂—C₆H₅, —CO—NH—C₆H₅, —CO—NH-(pOH)—C₆H₄,    —O—CH₂—C₆H₅ or —S-pCl—C₆H₄,-   R² represents a radical of the formula —XR¹² or —NR¹³R¹⁴,    -   in which    -   X represents a bond or an oxygen atom,    -   R¹² represents hydrogen, (C₁-C₄)-alkenyl, (C₁-C₄)-alkoxycarbonyl        or (C₁-C₄)-alkyl which are optionally substituted by pyridyl,        cyano, phenoxy, benzyl or by a radical of the formula —NR¹⁵R¹⁶,        -   in which        -   R¹⁵ and R¹⁶ are identical or different, and each represents            hydrogen, benzyl or (C₁-C₄)-alkyl,    -   R¹³ and R¹⁴ are identical or different, and each represents        hydrogen, (C₁-C₄)-alkyl or cyclopropyl,-   R³ represents hydrogen, amino or a radical of the formula-   or-    represents formyl, cyano, trifluoromethyl, cyclopropyl or pyridyl,    or represents (C₁-C₄)-alkyl which is optionally substituted by    halogen, (C₁-C₄)-alkoxycarbonyl, hydroxyl or by triazolyl, which for    its part may be substituted up to 3 times by (C₁-C₄)-alkoxycarbonyl,    and/or alkyl is optionally substituted by groups of the formulae    —OSO₂—CH₃ or (CO)_(a)—NR¹⁷R¹⁸,    -   in which    -   a represents a number 0 or 1,    -   R¹⁷ and R¹⁸ are identical or different, and each represents        hydrogen, phenyl or benzyl, or    -    represents C₁-C₄-alkyl which is optionally substituted by        (C₁-C₄)-alkoxycarbonyl, hydroxyl, phenyl or benzyl, where phenyl        or benzyl are optionally mono- or polysubstituted by identical        or different substituents from the group consisting of hydroxyl,        carboxyl, (C₁-C₄)-alkyl and (C₁-C₄)-alkoxy,    -    and/or (C₁-C₄)-alkyl is optionally substituted by radicals of        the formulae —NH—CO—CH₃ or —NH—CO—CF₃,    -   or    -   R¹⁷ and R¹⁸ together with the nitrogen atom form a morpholine,        piperidinyl or pyrrolidinyl ring,-   or-   R³ represents phenyl which is optionally substituted by methoxy,-   or-   R² and R³ together form a radical of the formula-   R⁴ represents hydrogen, methyl, benzoyl or acetyl,-   R⁵ represents pyridyl which is substituted up to 2 times by    identical or different substituents from the group consisting of    fluorine, chlorine, bromine, (C₁-C₄)-alkoxy and (C₁-C₄)-alkyl,    and salts thereof.

Particular preference is given to compounds of the general formulae (I)and (Ia) according to the invention,

in which

-   R¹ represents phenyl, furyl, thienyl, pyridyl, cyclopentyl,    cyclohexyl or represents radicals of the formulae-    where the abovementioned ring systems are optionally substituted up    to 2 times by identical or different substituents selected from the    group consisting of fluorine, chlorine, bromine, iodine, hydroxyl,    trifluoromethyl, nitro, SO₂—CF₃, methyl, cyano, amino,    trifluoromethoxy, carboxyl, methoxycarbonyl and radicals of the    formulae —CO—NH—CH₂—C(CH₃)₃, —CO—NH(CH₂)₂OH, —CO—NH—CH₂—C₆H₅,    —CO—NH—C₆H₅, —CO—NH-(pOH)—C₆H₄, —O—CH₂—C₆H₅ or —S-pCl—C₆H₄,-   R² represents a radical of the formula —XR¹² or —NR¹³R¹⁴,-    in which    -   X represents a bond or an oxygen atom,    -   R¹² represents hydrogen, (C₁-C₃)-alkenyl, (C₁-C₄)-alkoxycarbonyl        or (C₁-C₄)-alkyl which are optionally substituted by pyridyl,        cyano, phenoxy, benzyl or by a radical of the formula —NR¹⁵R¹⁶,        -   in which        -   R¹⁵ and R¹⁶ are identical or different, and each represents            hydrogen or methyl,    -   R¹³ and R¹⁴ are identical or different, and each represents        hydrogen, (C₁-C₃)-alkyl or cyclopropyl,-   R³ represents hydrogen, amino or represents a radical of the formula-   or-    represents formyl, cyano, trifluoromethyl, cyclopropyl or pyridyl,    or-    represents (C₁-C₄)-alkyl which is optionally substituted by    fluorine, chlorine, (C₁-C₃)-alkoxycarbonyl, hydroxyl or by    triazolyl, which for its part may be substituted up to 3 times by    (C₁-C₃)-alkoxycarbonyl, and/or alkyl is optionally substituted by    groups of the formulae —OSO₂—CH₃ or (CO)_(n)—NR¹⁷R¹⁸,-   in which    -   a represents a number 0 or 1,    -   R¹⁷ and R¹⁸ are identical or different, and each represents        hydrogen, phenyl or benzyl, or    -    represents (C₁-C₃)-alkyl which is optionally substituted by        (C₁-C₃)-alkoxycarbonyl, hydroxyl, phenyl or benzyl, where phenyl        or benzyl are optionally mono- or disubstituted by identical or        different substituents from the group consisting of hydroxyl,        carboxyl, (C₁-C₃)-alkyl and (C₁-C₃)-alkoxy,    -    and/or (C₁-C₄)-alkyl is optionally substituted by radicals of        the formulae —NH—CO—CH₃ or —NH—CO—CF₃,    -   or    -   R¹⁷ and R¹⁸ together with the nitrogen atom form a morpholine,        piperidinyl or pyrrolidinyl ring,-   or-   R³ represents phenyl which is optionally substituted by methoxy,-   or-   R² and R³ together form a radical of the formula-   R⁴ represents hydrogen, methyl, benzoyl or acetyl,-   R⁵ represents pyridyl which is substituted up to 2 times by    identical or different substituents from the group consisting of    fluorine, chlorine, (C₁-C₃)-alkoxy and (C₁-C₃)-alkyl,    and salts thereof.

Very particular preference is given to compounds of the general formulae(I) and (Ia) according to the invention,

-   in which-   R¹ represents phenyl which is optionally substituted up to 2 times    by identical or different substituents from the group consisting of    fluorine, chlorine, bromine, iodine, methyl and nitro,-   R² represents —XR¹² in which X represents oxygen and R¹² represents    straight-chain or branched alkyl having up to 4 carbon atoms,-   R³ represents methyl, ethyl or cyclopropyl,-   or-   R² and R³ together form a radical of the formula-   R⁴ represents hydrogen or acetyl,-   and-   R⁵ represents pyridyl which is substituted up to two times by    identical or different substituents from the group consisting of    fluorine and chlorine,    and salts thereof.

Even more preference is given to compounds of the general formula (I) or(Ia) according to the invention in which R⁵ represents 2-pyridyl whichcan be substituted by 1 to 2 fluorine atoms.

Very particular preference is also given to those compounds of thegeneral formulae (I) and (Ia) according to the invention which arelisted in Table A: TABLE A Structure

Very particular preference is given to the following compounds:

The compounds of the general formula (I) according to the invention canbe prepared by

[A] Reacting Aldehydes of the General Formula (II)R¹—CHO  (II)in whichR¹ is as defined above,with amidines or their hydrochlorides of the formula (III)

in whichR⁵ is as defined above,and compounds of the general formula (IV)R³—CO—CH₂—CO—R²  (IV)in whichR² and R³ are each as defined above,if appropriate in the presence of inert organic solvents, with orwithout addition of base or acid,or[B] Reacting Compounds of the General Formula (V)

in whichR¹, R² and R³ are each as defined above,with amidines of the general formula (III)

in whichR⁵ is as defined above,if appropriate in the presence of inert organic solvents at temperaturesbetween 20° C. and 150° C., with or without addition of base or acid,or[C] Reacting Aldehydes of the General Formula (II)R¹—CHO  (II)in whichR¹ is as defined above,with compounds of the general formula (VI)

in whichR² and R³ are each as defined above,and amidines of the general formula (III) as described above,or[D] Reacting Aldehydes of the General Formula (II) with Compounds of theGeneral Formula (IV) and Imino Ethers of the General Formula (VII)

in whichR⁵ is as defined above,andR¹ represents (C₁-C₄)-alkyl,in the presence of ammonium salts.

The processes according to the invention can be illustrated using thefollowing schemes as examples:

Solvents which are suitable for all process variants A, B, C and D areall inert organic solvents. These preferably include alcohols, such asethanol, methanol, isopropanol, ethers, such as dioxane, diethyl ether,tetrahydrofuran, glycol monomethyl ether, glycol dimethyl ether orglacial acetic acid, dimethyl formamide, dimethyl sulphoxide,acetonitrile, pyridine and hexamethylphosphoric triamide.

The reaction temperatures can be varied within a relatively wide range.In general, the reaction is carried out between 20 and 150° C., butpreferably at the boiling point of the solvent in question.

The reaction can be carried out at atmospheric pressure, or else atelevated pressure. In general, the reaction is carried out atatmospheric pressure.

The reaction can be carried out with or without addition of base oracid; however, it has been found that a reaction according to theinvention is preferably carried out in the presence of relatively weakacids, such as, for example, acetic acid or formic acid.

The aldehydes of the general formula (II) used as starting materials areknown or can be prepared by methods known from the literature (cf. T. D.Harris and G. P. Roth, J. Org. Chem. 44, 146 (1979), GermanOffenlegungsschrift 2 165 260, July 1972, German Offenlegungsschrift 2401 665, July 1974, Mijano et al., Chem. Abstr. 59, (1963), 13 929 c, E.Adler and H.-D. Becker, Chem. Scand. 15, 849 (1961), E. P. Papadopoulos,M. Mardin and Ch. Issidoridis, J. Org. Chem. Soc. 78, 2543 (1956)).

The ylidene-β-keto esters of the formula (V) used as starting materialscan be prepared by methods known from the literature [cf. G. Jones, “TheKnoevenagel Condensation”, in Organic Reactions, Vol. XV, 204 ff.(1967)].

The enaminocarboxylic esters of the formula (VI) and the imino ethers ofthe general formula (VII) used as starting materials are known or can beprepared by methods known from the literature [cf. S. A. Glickman and A.C. Cope, J. Am. Chem. Soc. 67, 1017 (1945)].

The β-ketocarboxylic esters of the general formula (IV) used as startingmaterials are known or can be prepared by methods known from theliterature [for example D. Borrmann, “Umsetzung von Diketen mitAlkoholen, Phenolen und Mercaptanen”, in Houben-Weyl, Methoden derorganischen Chemie, Vol. VII/4, 230 ff (1968); Y. Oikawa, K. Sugano andO. Yonemitsu, J. Org. Chem. 43, 2087 (1978)].

Some of the compounds of the general formula (III) are known, or, in thecase where R⁵ is difluorinated pyridyl, are novel, and they can beprepared by reacting compounds of the formula (VIII)R⁵—CN  (VIII)in whichR⁵ is as defined above,in the customary way via the imino ethers and finally with ammoniumchloride in methanol [cf. in this context W. K. Fife, Heterocycles 22,93-96 (1984); T. Sakamoto, S. Kaneda, S. Nishimura, H. Yamanaka, Chem.Pharm. Bull. 33, 565-571 (1986)] or other processes known from theliterature, such as, for example, Garigipati, Tetrahedron Lett. 1990,pp. 1969-1972, Boere et al., J. Organomet. Chem. 1987, 331, 161, Catonet al., J. Chem. Soc. 1967, 1204.

All process steps are carried out at atmospheric pressure and in atemperature range of from 0° C. to 130° C., preferably from 20° C. to100° C.

Thus, the invention also relates to an intermediate of the formula below

and its salts from which preferred end products can be prepared. Withrespect to the salts of this compound, reference is made to theabovementioned acid addition salts and in particular to thehydrochloride. This compound is prepared as described in the examples,and, in this respect, reference is also made to the reaction schemeshown below.

The compounds of the formula (VIII) are known per se or can be preparedby known processes similarly to Example I and II by reacting pyridinesof the general formula (IX)R⁵—H  (IX)in which the hydrogen is ortho to the nitrogen and in which R⁵ is asdefined above, initially at from 50 to 150° C., preferably at 100° C.,in H₂O₂/glacial acetic acid to give the corresponding N-oxides, followedby a reaction with trimethylsilyl cyanide (TMSCN) by processes knownfrom the literature in the abovementioned inert solvents, preferablyacetonitrile, THF, toluene at room temperature or at reflux temperature,if appropriate with addition of bases such as triethylamine or DBU,or by replacing, in compounds of the formula (X)

in which Y and Z represent the substitution radicals of the pyridyl ringmentioned under R⁵, the chlorine with cyanide, using cyanides, such aspotassium cyanide or copper cyanide,or by reacting, in the case where R⁵ represents difluoropyridyl,compounds of the formula (XI)

in which Y′ and Z′ are identical or different, and each representschlorine or bromine, with alkali metal or ammonium fluorides, preferablypotassium fluoride, by processes known from the literature, in polarsolvents, such as, for example, polyglycols and ethers thereof, DMSO orsulpholane, if appropriate with addition of phase-transfer catalysts, ina halogen-fluorine exchange reaction.

Thus, the invention also relates to a compound of the formula below fromwhich the corresponding amidine intermediate can be prepared in themanner described in the examples:

The above process is, with respect to the 3,5-difluoropyridyl compounds,illustrated in an exemplary manner by the following reaction scheme:

The antiviral activity of the compounds according to the invention wasinvestigated following the methods described by Sells et al. (M. A.Sells, M.-L. Chen, and G. Acs (1987) Proc. Natl. Acad. Sci. 84,1005-1009) and Korba et al. (B. E. Korba and J. L. Gerin (1992)Antiviral Research 19, 55-70).

The antiviral tests were carried out in 96-well microtitre plates. Onlygrowth medium and HepG2.2.15 cells were added to the first vertical rowof the plate. This row served as virus control.

Stock solutions of the test compounds (50 mM) were initially dissolvedin DMSO, and further dilutions were prepared in the growth medium ofHepG2.2.15. The compounds according to the invention, usually in a testconcentration of 100 μM (1st test concentration), were in each casepipetted into the second vertical test row of the microtitre plate andsubsequently diluted, by a factor of 2 each time, up to 2¹⁰-fold, usinggrowth medium plus 2% of foetal calf serum (volume 25 μl).

225 μl of a HepG2.2.15 cell suspension (5×10⁴ cells/ml) in growth mediumplus 2% foetal calf serum were then added to each well of the microtitreplate.

The test batch was incubated at 37° C., 5% CO₂, for 4 days.

The supernatant was subsequently siphoned off and discarded, and 225 μlof freshly prepared growth medium were added to the wells. Once more,the compounds according to the invention were added, in each case as asolution 10-fold-concentrated, in a volume of 25 μl. The batches wereincubated for another 4 days.

Before the supernatants were harvested for determining the antiviraleffect, the HepG2.2.15 cells were examined under the light microscope orby biochemical detection methods (for example Alamar Blue staining orTrypan Blue staining) for cytotoxic changes.

The supernatants were subsequently harvested and, by means of reducedpressure, siphoned onto 96-well dot blot chambers covered with a nylonmembane (in accordance with the specifications of the manufacturer).

Determination of the Cytotoxicity

Substance-induced cytotoxic or cytostatic changes in the HepG2.2.15cells were determined as changes in the cell morphology, for exampleunder a light microscope. Such substance-induced changes of theHepG2.2.15 cells in comparison with untreated cells could be observed,for example, as cell lysis, vacuolization or changed cell morphology.50% cytotoxicity (Tox.−50) means that 50% of the cells have a morphologywhich is similar to the corresponding cell control.

The compatibility of some of the compounds according to the inventionwas additionally tested on other host cells, such as, for example, HeLacells, primary peripheral human blood cells or transformed cell lines,such as H-9 cells.

At concentrations of the compounds according to the invention of >10 μM,no cytotoxic changes were observed.

Determination of the Antiviral Activity

After transfer of the supernatants onto the nylon membrane of the blotapparatus (see above), the supernatants of the HepG2.2.15 cells weredenatured (1.5 M NaCl/0.5 N NaOH), neutralized (3 M NaCl/0.5 M Tris HCl,pH 7.5) and washed (2×SSC). By incubation of the filters at 120° C. for2-4 hours, the DNA was subsequently baked onto the membrane.

Hybridization of the DNA

The viral DNA of the treated HepG2.2.15 cells on the nylon filters wasusually detected using non-radioactive digoxygenin-labelled hepatitisB-specific DNA probes which were in each case in accordance with thespecifications of the manufacturer labelled with digoxygenin, purifiedand used for hybridization.

The prehybridization and hybridization was carried out in5×SSC,1×blocking reagent, 0.1% N-lauroylsarcosine, 0.02% SDS and 100 μgof DNA from herring sperm. The prehybridization was carried out at 60°C. for 30 minutes and the specific hybridization was carried out using20 to 40 μg/ml of the digoxygenated denatured HBV-specific DNA (14hours, 60° C.). The filters were subsequently washed.

Determination of HBV DNA by Digoxygenin Antibodies

The digoxygenin-labelled DNA was detected immunologically in accordancewith the specifications of the manufacturer:

The filters were washed and prehybridized in a blocking agent (inaccordance with the specifications of the manufacturer). They weresubsequently hybridized for 30 minutes using an anti-DIG antibody linkedto alkaline phosphatase. After a washing step, the substrate of alkalinephosphatase, CSPD, was added, incubated with the filters for 5 minutes,subsequently wrapped in plastic film and incubated at 37° C. for afurther 15 minutes. The chemiluminescence of the Hepatitis B-specificDNA signals was visualized by exposition of the filters on an X-ray film(incubation, depending on the signal strength: 10 minutes to 2 hours).

The half-maximum inhibitory concentration (IC-50, inhibitoryconcentration 50%) was determined as the concentration at which thehepatitis B-specific band was reduced by 50% in comparison with anuntreated sample by the compound according to the invention.

Surprisingly, the treatment of the hepatitis B virus-producingHepG2.2.15 cells with the compounds according to the invention resultedin a reduction of viral DNA in the cell culture supernatant, the viralDNA being released by the cells into the cell culture supernatant in theform of virions.

The compounds according to the invention have a novel unforeseeable anduseful action against viruses. Surprisingly, they are antivirally activeagainst hepatitis B (HBV) and are therefore suitable for treatingvirus-induced diseases, in particular acute and chronically persistingHBV virus infections. A chronic viral disease caused by HBV can lead toclinical pictures of various gravity; as is known, chronic hepatitis Bvirus infection frequently results in cirrhosis of the liver and/orhepatocellular carcinoma.

Examples which may be mentioned of areas of indication for the compoundsusable according to the invention are:

The treatment of acute and chronic virus infections which may lead to aninfectious hepatitis, for example infections with hepatitis B viruses.Particular preference is given to the treatment of chronic hepatitis Binfections and the treatment of acute hepatitis B virus infection.

The present invention encompasses pharmaceutical formulations which, inaddition to non-toxic inert pharmaceutically acceptable excipients,contain one or more compounds of the formulae (I), (Ia) or of Table A orwhich comprise one or more active compounds of the formulae (I), (Ia)and (Ib), and also encompasses processes for producing theseformulations.

In the abovementioned pharmaceutical formulations, the active compoundsof the formulae (I), (Ia) and (Ib) should be present in a concentrationof approximately 0.1-99.5% by weight, preferably of approximately0.5-95% by weight of the total mixture.

The abovementioned pharmaceutical formulations may, in addition to thecompounds of the formulae (I), (Ia) and (Ib), also contain furtherpharmaceutically active compounds.

The abovementioned pharmaceutical formulations are produced in acustomary manner by known methods, for example by mixing the activecompound(s) with the excipient(s).

In general, it has been found to be advantageous both in human andveterinary medicine to administer the active compound(s) in totalamounts of from approximately 0.5 to approximately 500, preferably 1-100mg/kg of body weight per 24 hours, if appropriate in the form of severalindividual doses, to obtain the desired results. An individual dosepreferably contains the active compound(s) in amounts of fromapproximately 1 to approximately 80, in particular 1-30 mg/kg of bodyweight. However, it may be necessary to deviate from the specifieddosages, depending on the nature and the body weight of the object to betreated, the nature and the severity of the disease, the formulationtype and the administration of the medicament, and the time or intervalwithin which administration is carried out.

Starting Materials

EXAMPLE I 3-Fluoropyridine N-oxide

11.10 g (114.324 mmol) of 3-fluoropyridine are dissolved in 74.00 ml ofacetic acid. 22.20 ml of H₂O₂ are added, and the mixture is stirred at abath temperature of 100° C. for 7 hours. The mixture is thenconcentrated to 30 ml, 30 ml of water are added and the mixture is oncemore concentrated to 30 ml. The solution is stirred withdichloromethane, made alkaline by addition of K₂CO₃, the phases areseparated and the aqueous phase is extracted twice with dichloromethane,dried and concentrated.

Yield: 11.5 g (88.9%)

m.p.: 66-68° C.

EXAMPLE II 2-Cyano-3-fluoropyridine

5.20 g (45.980 mmol) of the compound from Example I are dissolved in 50ml of acetonitrile. Under argon, 13.70 g (138.092 mmol) oftrimethylsilylnitrile are added, and 12.80 ml of triethylamine areslowly admixed. The solution is stirred under reflux for 7 hours andthen at room temperature overnight. The solution is then concentratedusing a water pump, taken up in dichloromethane, shaken 2× with 50 ml of2N sodium carbonate, washed with water, dried and concentrated.

Yield (crude): 5.3 g (oil)

Column chromatography: methylene chloride to methylene chloride/ethylacetate 10:1

The oil solidifies!

EXAMPLE III 2-Amidino-3-fluoropyridine hydrochloride

10.30 g (84.355 mmol) of the compound from Example II are dissolved in30 ml of methanol. The solution is admixed with a solution of 0.40 g(17.391 mmol) of sodium in 65 ml of methanol and stirred at 20° C. for72 hours. 5.44 g (101.682 mmol) of ammonium chloride (ground in amortar) and 17.39 mmol (1.04 ml) of acetic acid are added and themixture is stirred at 40° C. for 28 hours and cooled. Insoluble salt isfiltered off with suction (1.78 g) and the filtrate is concentrated,concentrated with acetone and subsequently stirred with acetone,filtered off with suction and washed.

Yield: 10.6 g

m.p.: ≈150° C. decomp.

EXAMPLE IV 2-cyano-3,5-dichloro-pyridine

Method 1:

26 g (0.158 mol) of 3,5-dichloro-pyridine 1-oxide (Johnson et al., J.Chem. Soc. B, 1967, 1211) are dissolved in 80 ml of CH₂Cl₂ and admixedsuccessively with 21.8 ml (0.174 mol) of trimethylsilyl cyanide and 14.6ml (0.158 mol) of dimethylcarbamoyl chloride and stirred at roomtemperature for 48 h. The mixture is admixed with 100 ml of a 10%strength NaHCO₃ solution and stirred vigorously for 10 min. The phasesare separated, the aqueous phase is extracted once with CH₂Cl₂ and thecombined organic phases are dried and concentrated. The residue ischromatographed over silica gel using CH₂Cl₂ and recrystallized from alittle methanol.

This gives 11 g (40.2%) of 2-cyano-3,5-dichloro-pyridine (m.p.: 102°C.).

Method 2:

By the method of Troschuetz, R. et al., J. Heterocycl. Chem. 1996, 33,1815-1821, 150 ml of diethylene glycol dimethyl ether (diglyme), 47.68 g(0.261 mol) of 2,3,5-trichloropyridine, 2.0 g (0.005 mol) oftetraphenylphosphonium bromide, 4.0 g (0.024 mol) of finely powderedpotassium iodide and 75.0 g (0.838 mol) of copper(I) cyanide are addedunder nitrogen, and the mixture is stirred at reflux for 24 hours.Another 100 ml of diglyme, 2.0 g (0.005 mol) of tetraphenylphosphoniumbromide, 4.0 g (0.024 mol) of finely powdered KI and 75 g (0.838 mol) ofCuCN are subsequently added, and the mixture is stirred at reflux for afurther 89 hours. The mixture is cooled to room temperature and filteredoff with suction, and the filtrate is freed distillatively from most ofthe diglyme. The residue is taken up in toluene and washed with anaqueous solution of Mohr's salt and then with NaHCO₃ solution (peroxidetest). The mixture is then washed free of diglyme using water andfiltered through Celite, the filtrate is dried over MgSO₄ and thesolution is concentrated. This gives 18.0 g (40.0%) of2-cyano-3,5-dichloropyridine.

EXAMPLE V 3,5-Difluoro-pyridine-2-carbonitrile

50 g (0.29 mol) of 3,5-dichloropyridine-2-carbonitrile (Example IV),33.6 g (0.58 mol) of potassium fluoride and 10 g of polyethylene glycol8000 are admixed with 125 ml of DMSO and heated at 160° C. for 30 min.After cooling, the product, together with the DMSO, is distilled offunder high vacuum, and the distillate is poured into water, extractedwith toluene and dried over Na₂SO₄. The product is reacted further as asolution in toluene.

(R_(f) value: 0.43, cyclohexane/ethyl acetate=7.3)

EXAMPLE VI 3,5-difluoro-2-pyridinecarboximidamide hydrochloride

33.4 g (0.624 mol) of ammonium chloride are suspended in 1 l of tolueneand cooled to 0-5° C. 328 ml of trimethylaluminum (2 M in hexane, 0.624mol) are added dropwise, and the mixture is stirred at RT until theevolution of methane has ceased. The solution of3,5-dichloro-pyridine-2-carbonitrile in toluene (solution from ExampleV) is then added dropwise, and the mixture is then stirred at 80° C.overnight. After cooling to from 0 to −5° C., MeOH is added dropwiseuntil the evolution of gas has ceased, the salts are filtered off withsuction and washed to 2× with a little MeOH. The mixture is concentratedusing a rotary evaporator and the residue is dissolved in 500 ml ofCH₂Cl₂/MeOH (9:1) and once more filtered off with suction from inorganicsalts. The mixture is concentrated using a rotary evaporator, giving23.6 g (39.1%) of 3,5-difluoro-2-pyridinecarboximidamide ashydrochloride (m.p.: 183° C.).

¹H-NMR (DMSO-D6): 8.3-8.45(m, 1H), 8.8 (d, J=2 Hz, 1H), 9.7(s, broad,4H) ppm.

EXAMPLE VII Methyl 2-acetyl-3-(2-chloro-4-fluorophenyl)-2-propynoate

50 g (315 mmol) of 2-chloro-4-fluoro-benzaldehyde and 36.6 g (315 mmol)of methyl acetoacetate are dissolved in 150 ml of isopropanol andadmixed with 1.7 ml of piperadine acetate. The mixture is stirred atroom temperature overnight and then diluted with methylene chloride andextracted with water, dried over sodium sulphate and concentrated. Thecrude product is reacted further, as cis-trans mixture.

PREPARATION EXAMPLES Example 1 Ethyl4-(2-bromophenyl)-2-(3-fluoropyridin-2-yl)-6-methyl-1,4-dihydro-pyrimidin-5-carboxylate

92.50 mg (500 μmol) of 2-bromobenzaldehyde in 3.00 ml of ethanol areadmixed successively with 65.0 mg of ethyl acetoacetate, 91.80 mg of thecompound from Example III and 43.06 mg of sodium acetate, and themixture is boiled for 6 hours. The mixture is cooled, concentrated,dissolved in 2 ml of 1N HCl and 4 ml of H₂O and ethyl acetate, thephases are separated, the organic phase is extracted with 1 ml of 1N HCland water and the combined aqueous phases are washed with ether. Theaqueous phase is made alkaline using dilute ammonia solution, extractedwith ethyl acetate, and the organic phase is washed with H₂O, dried andconcentrated. The residue is dissolved in a little ether andcrystallized. The crystals are filtered off with suction, washed withether and dried at 60° C. under reduced pressure.

TLC: pure (toluene/ethyl acetate=4:1)

Yield: 92 mg (44%)

m.p.: 163-165° C.

The compounds listed in Table I are prepared by the method of Example 1:TABLE 1 Example No.: Structure m.p. [° C.] R_(f) 2

121-123 — 3

>120 — 4

152-53 — 5

142-143 — 6

142-143 — 7

139-140 — 8

173-175 — 9

174-175 — 10

127-129 — 11

133-134 — 12

110-111 — 13

222 decomposition — 14

140-142 — 15

165-167 — 16

180-182 — 17

148-149 — 18

121-123 — 19

151-153 — 20

117-119 (−)-enantiomer of Example 4 — 21

138-140 — 22

163-165 — 23

124-126 — 24

123-125 — 25

145-146 — 26

120-122 — 27

144-146 — 28

135-137 — 29

143-144 — 30

156-157 — 31

134-135 — 32

247-248 — 33

119-120 (−)-enantiomer — 34

129-130° C. (−) enantiomer — 35

(−) enantiomer of Ex. 19 — 36

126-127 — 37

156-158 — 38

162-163 — 39

167-169 — 40

129-130 — 41

163-164 — 42

120-122 — 43

103-104 — 44

210-212 — 45

132-133° C. — 46

95-96° C. — 47

154-155° C. — 48

131-132° C. — 49

137-138° C. — 50

184-186° C. — 51

133-134° C. — 52

135-136° C. — 53

131° C. — 54

amorphous 0.17 (cyclo- hexane/ ethy acetate =7:3) 55

124° C. — 56

141° C. — 57

132° C. — 58

amorphous 0.14 (cyclo- hexane/- ethyl acetate =7:3) 59

amorphous 0.23 (cyclo- hexane/ ethyl acetate =7:3) 60

126° C. —

Example 61 Methyl4-(2-chloro-4-fluorophenyl)-2-(3,5-difluoro-2-pyridinyl)-6-methyl-1,4-dihydropyrimidine-5-carboxylate(see table)

4.5 g (23.2 mmol) of 3,5-difluoro-2-pyridinecarboximidamidehydrochloride (Example VI) with 7.7 g (30 mmol) of methyl2-acetyl-3-(2-chloro-4-fluorophenyl)-2-propynoate (Example VII) and 2.3g (27.9 mmol) of sodium acetate are dissolved or suspended in 120 ml ofisopropanol and boiled under reflux for 4 h.

The mixture is cooled to room temperature and then filtered off withsuction from inorganic salts and concentrated. The residue is taken upin 30 ml of 1N HCl and 35 ml of ethyl acetate, and the phases areseparated. The ethyl acetate phase is re-extracted once using 30 ml of1N HCl. The combined aqueous phases are extracted three times with 10 mlof diethyl ether each time. The aqueous phase is made alkaline usingNaOH and extracted with ethyl acetate. The organic phases are dried overNa₂SO₄ and concentrated.

This gives 7.4 g (80%) of product. (m.p.: 126° C.)

¹H-NMR (DMSO-D₆): 2.4(s, 3H), 3.5(s, 3H), 6.0(s, 1H), 7.2(m, 1H), 7.4(m,2H), 8.0(m, 1H), 8.55(d, J=2 Hz, 1H), 9.75(s, NH) ppm.

The (−)-enantiomer was obtained after separation of the enantiomers onchiral columns (Chiralpak AS from Baker, mobile phasen-heptane/ethanol=8:2).

m.p.: 117° C. (from ethanol)

Spec. rot.: −62.8° (MeOH) TABLE 2 Example No.: Structure [M + H] MS ES +61

117° C. (ethanol) (−)-enantiomer — 62

amorphous (−)-enantiomer 0.23 (cyclohexane/ethyl acetate = 7:3) 63

amorphous 0.36 (toluene/-ethyl acetate = 1:1) (−)-enantiomer 64

119-120° C. (−)-enantiomer 65

159° C. — 66

154° C. — 67

amorphous 0.33 (toluene/-ethyl acetate = 1:1) (−)-enantiomer 68

amorphous 0.30 (cyclohexane/ethyl acetate = 7:3) 69

152° C. 0.35 (cyclohexane/ethyl acetate = 7:3) 70

amorph 0.33 (toluene/-ethyl acetate = 1:1) 71

91-93° C. (−) enantiomer 72

amorphous 0.20 (cyclohexane/ethyl acetate = 1:1) 73

amorphous 0.27 (CH₂Cl₂/ MeOH = 95:5) 74

362 75

376 76

371 77

372 78

385 79

408 80

421 81

453 82

466 83

425 84

371m.p.[° C.] = melting point in degrees Celsius

1.-8. (canceled)
 9. The compound of the formula:

or a salt thereof.
 10. The compound of the formula:

11.-16. (canceled)